Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
R, C = map(int, input().split())
c = [list(input()) for _ in range(R)]
d = {}
q = [(0, 0, 0)]
d[0, 0] = 0
while q != []:
    (y, x, z) = q.pop(0)
    for v, w in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
        t = x + v
        u = y + w
        if t < 0 or t >= C or u < 0 or u >= R:
            continue
        if c[u][t] == '.' and (u, t) not in d:
            q.append((u, t, z + 1))
            d[u, t] = z + 1
if (R - 1, C - 1) not in d:
    ans = -1
else:
    ans = R * C - d[R - 1, C - 1] - 1
    for i in c:
        for j in i:
            if j == '#':
                ans -= 1
print(ans)